Many electronic devices, such as those used for radio communications, support accessory connections for various functions. For example, a radio communication device may include an accessory interface that allows connection for an external audio accessory such as a microphone, an external speaker, or the like. Audio accessories come in a variety of configurations and may be available from several vendors. Generally, specifications standards established for the audio accessories govern the impact of these accessories on internal audio signal lines of the electronic device.
In many cases, audio signal processing components within the electronic device are optimized to work with a selected number of audio accessories. However, because of manufacturing variations for audio accessories, and because of the potential for unanticipated combinations of simultaneously attached audio accessories, it is difficult to design audio signal processing components which will properly accommodate all such variations and combinations. Consequently, the coupling of certain audio accessories to the electronic device may yield an audio response that is unsuitable or undesirable for other signal processing. For example, a radio may use a speech coder that depends on audio signals having a flat response. When an audio accessory is coupled which distorts the audio response, the function of the speech coder may be adversely affected.
Generally, radio designers accommodate variations in audio signal paths through filters and other signal processing components employed in the design of a circuit. The provision of these additional components can add considerable time and expense to the design process, but yet does not usually provide a total solution because of the coupling of unanticipated accessories or combinations thereof. As a result, an electronic device that was designed to perform within certain specifications for audio signal processing may not continue to meet those specifications when certain audio accessories are coupled. It is desirable to provide a more flexible solution to accommodate various accessories which may be coupled to an electronic device in order to ensure consistent performance. Hence, a new approach to the accommodation of audio accessories is needed.